THE LONG-TERM GROWTH OF NORMAL HUMAN B CELLS

The feasibility of establishment of continuously proliferating growth factor-dependent human B lymphocytes was investigated. Normal B lymphocytes prepared from peripheral venous blood were stimulated with a variety of known polyclonal B cell activators, in the continuous presence of various cytokine preparations. Continuously proliferating growth factor-dependent B cell populations were obtained from cultures activated with either insoluble anti-IgM ((mu)-chain specific), soluble anti-IgM, heat-killed Staphylococcus aureus Cowen I (SAC), or dextran sulphate (DxS), in the continuous presence of exogenously added growth factor preparations containing either IL-1, IL-2 and BCGF, or BCGF alone. Although growth factor-dependent B cell lines were obtained via all three methods of activation, the correlation of mode of activation and growth factor preparation proved to be critical. B cell lines could not be established with anti-(mu) activation in the presence of only BCGF; however, B cell lines were successfully obtained with SAC or DxS activation from those cultures continuously replenished with only BCGF. These cultured B lymphocyte populations were routinely maintained in logarithmic-phase growth in the presence of exogenously added growth factor, and exhibited a population doubling time of approximately 36 hours. They were shown to specifically absorb BCGF, suggesting the presence of membrane receptors for it. Also, these cultured B cells have been utilized for the development of a microassay for the assessment of a M(,r) 12,000-14,000 B cell growth factor activity that is accurate, sensitive, and precise. The pronounced sensitivity of this bioassay beyond that of the conventional peripheral blood B cell assay has aided in the purification to homogeneity of natural product extracellular BCGF (EC-BCGF), and in the determination of the nucleotide sequence for a gene coding for a protein exhibiting BCGF activity. Additionally, these B cell lines specifically absorb, and proliferate in the presence of, an affinity-purified M(,r) 60,000 trypsin-sensitive intracellular protein derived from freshly isolated human T lymphocytes, providing evidence for a putative intracellular precursor of EC-BCGF, or a novel high molecular weight BCGF species. ^

Understanding the selective area growth of GaN nanocolumns by MBE using Ti nanomasks

The influence of the substrate temperature, III/V flux ratio, and mask geometry on the selective area growth of GaN nanocolumns is investigated. For a given set of growth conditions, the mask design (diameter and pitch of the nanoholes) is found to be crucial to achieve selective growth within the nanoholes. The local III/V flux ratio within these nanoholes is a key factor that can be tuned, either by modifying the growth conditions or the mask geometry. On the other hand, some specific growth conditions may lead to selective growth but not be suitable for subsequent vertical growth. With optimized conditions, ordered GaN nanocolumns can be grown with a wide variety of diameters. In this work, ordered GaN nanocolumns with diameter as small as 50 nm are shown.

Tissue-specific expression of herpes simplex virus thymidine kinase gene delivered by adeno-associated virus inhibits the growth of human hepatocellular carcinoma in athymic mice

About 70% of hepatocellular carcinomas are known to express α-fetoprotein, which is normally expressed in fetal but not in adult livers. To induce herpes simplex virus-thymidine kinase expression in these cancer cells, we constructed an adeno-associated viral vector containing the HSV-TK gene under the control of the α-fetoprotein enhancer and albumin promoter. We previously demonstrated in vitro that although this vector can transduce a variety of human cells, only transduced AFP and albumin-expressing hepatocellular carcinoma cell lines were sensitive to killing by ganciclovir (GCV). In the present study, we explored the effect of this vector on hepatocellular carcinoma cells in vivo. Subcutaneous tumors generated in nude mice by implanting hepatocellular carcinoma cells previously transduced with this vector shrank dramatically after treatment with GCV. Bystander effect was also observed on the tumors generated by mixing transduced and untransduced cells. To test whether the tumor cells can be transduced by the virus in vivo, we injected the recombinant adeno-associated virus into tumors generated by untransduced hepatocarcinoma cell line. Tumor growth were retarded after treatment with GCV. These experiments demonstrate the feasibility of in vivo transduction of tumor cell with rAAV.

Improved adenovirus packaging cell lines to support the growth of replication-defective gene-delivery vectors.

Adenovirus (Ad) vectors have been extensively used to deliver recombinant genes to a great variety of cell types in vitro and in vivo. Ad-based vectors are available that replace the Ad early region 1 (E1) with recombinant foreign genes. The resultant E1-deleted vectors can then be propagated on 293 cells, a human embryonal kidney cell line that constitutively expresses the E1 genes. Unfortunately, infection of cells and tissues in vivo results in low-level expression of Ad early and late proteins (despite the absence of E1 activity) resulting in immune recognition of virally infected cells. The infected cells are subsequently eliminated, resulting in only a transient expression of foreign genes in vivo. We hypothesize that a second-generation Ad vector with a deletion of viral genes necessary for Ad genome replication should block viral DNA replication and decrease viral protein production, resulting in a diminished immune response and extended duration of foreign gene expression in vivo. As a first step toward the generation of such a modified vector, we report the construction of cell lines that not only express the E1 genes but also constitutively express the Ad serotype 2 140-kDa DNA polymerase protein, one of three virally encoded proteins essential for Ad genome replication. The Ad polymerase-expressing cell lines support the replication and growth of H5ts36, an Ad with a temperature-sensitive mutation of the Ad polymerase protein. These packaging cell lines can be used to prepare Ad vectors deleted for the E1 and polymerase functions, which should facilitate development of viral vectors for gene therapy of human diseases.

Direct seeding to restore rainforest species: Microsite effects on the early establishment and growth of rainforest tree seedlings on degraded land in the wet tropics of Australia

Reforestation in tropical areas is usually attempted by planting seedlings but, direct seeding (the artificial addition or sowing of seed) may be an alternative way of accelerating forest recovery and successional processes. This study investigated the effects of various sowing treatments (designed to create different microsite conditions for seed germination) and seed sizes on the early establishment and growth of directly sown rainforest tree species in a variety of experimental plots at three sites in the wet tropical region of north-cast Queensland, Australia. The different sowing treatments were found to have significant effects on seedling establishment. Broadcast sowing treatments were ineffective and resulted in very poor seedling establishment and high seed wastage. Higher establishment rates occurred when seeds were buried. Seed size was found to be an important factor affecting establishment in relation to micro-site condition. In general, larger seeded species had higher establishment rates at all three sites than species of small and intermediate seed size, but only in sowing treatments where seeds were buried. Overall these results suggest that direct sowing of seed can be used as a too] to accelerate recolonisation of certain rainforest tree species on degraded tropical lands, but initial success will be dependent on the choice of sowing method and its suitability for the seed types selected. The results also indicate that the recruitment of naturally dispersed tree species at degraded sites is likely to be severely limited by the availability of suitable microsites for seed germination. Consequently the natural recovery of degraded sites via seed rain can be expected to be slow and unpredictable, particularly in areas where soil compaction has occurred. (c) 2006 Elsevier B.V. All rights reserved.

Growth of some varieties of Leibniz-Poisson algebras

2010 Mathematics Subject Classification: 17A32, 17B63.

Growth of the Food Service Industry

The food service industry has come into its own recognition as a growing segment of the total food market. The author looks at the recent expansion of the industry in volume, diversification of restaurant types, and menu variety

Growth of boehmite nanofibers by assembling nanoparticles with surfactant micelles

It is known that boehmite (AlOOH) nanofibers formed in the presence of nonionic poly(ethylene oxide) (PEO) surfactant at 373 K. A novel approach is proposed in this study for the growth of the boehmite nanofibers: when fresh aluminum hydrate precipitate was added at regular interval to initial mixture of boehmite and PEO surfactant at 373 K, the nanofibers grow from 40 to 50 nm long to over 100 nm. It is believed that the surfactant micelles play an important role in the nanofiber growth: directing the assembly of aluminum hydrate particles through hydrogen bonding with the hydroxyls on the surface of aluminum hydrate particles. Meanwhile a gradual improvement in the crystallinity of the fibers during growth is observed and attributed to the Ostwald ripening process. This approach allows us to precisely control the size and morphology of boehmite nanofibers using soft chemical methods and could be useful for low temperature, aqueous syntheses of other oxide nanomaterials with tailorable structural specificity such as size, dimension and morphology.

From the consciousness industry to the creative industries : consumer-created content, social network markets, & the growth of knowledge

In studies of media industries, too much attention has been paid to providers and firms, too little to consumers and markets. But with user-created content, the question first posed more than a generation ago by the uses & gratifications method and taken up by semiotics and the active audience tradition (‘what do audiences do with media?’), has resurfaced with renewed force. What’s new is that where this question (of what the media industries and audiences did with each other) used to be individualist and functionalist, now, with the advent of social networks using Web 2.0 affordances, it can be re-posed at the level of systems and populations as well.

Uses of YouTube : digital literacy and the growth of knowledge

I invented YouTube. Well, not YouTube exactly, but something close – something called YIRN; and not by myself exactly, but with a team. In 2003-5 I led a research project designed to link geographically dispersed young people, to allow them to post their own photos, videos and music, and to comment on the same from various points of view – peer to peer, author to public, or impresario to audience. We wanted to find a way to take the individual creative productivity that is associated with the Internet and combine it with the easy accessibility and openness to other people’s imagination that is associated with broadcasting; especially, in the context of young people, listening to the radio. So we called it the Youth Internet Radio Network, or YIRN.

Ceramic membranes for separation of proteins and DNA by in situ growth of alumina nanofibres with a nanomesh of metal oxide nanofibres

Ceramic membranes were fabricated by in situ synthesis of alumina nanofibres in the pores of an alumina support as a separation layer, and exhibited a high permeation selectivity for bovine serum albumin relative to bovine hemoglobin (over 60 times) and can effectively retain DNA molecules at high fluxes.

Porous polyurethane coatings bonded onto surface-modified titanium substrates for the growth of an endothelial cell layer

Cardiovascular diseases refer to the class of diseases that involve the heart or blood vessels (arteries and veins). Examples of medical devices for treating the cardiovascular diseases include ventricular assist devices (VADs), artificial heart valves and stents. Metallic biomaterials such as titanium and its alloy are commonly used for ventricular assist devices. However, titanium and its alloy show unacceptable thrombosis, which represents a major obstacle to be overcome. Polyurethane (PU) polymer has better blood compatibility and has been used widely in cardiovascular devices. Thus one aim of the project was to coat a PU polymer onto a titanium substrate by increasing the surface roughness, and surface functionality. Since the endothelium of a blood vessel has the most ideal non-thrombogenic properties, it was the target of this research project to grow an endothelial cell layer as a biological coating based on the tissue engineering strategy. However, seeding endothelial cells on the smooth PU coating surfaces is problematic due to the quick loss of seeded cells which do not adhere to the PU surface. Thus it was another aim of the project to create a porous PU top layer on the dense PU pre-layer-coated titanium substrate. The method of preparing the porous PU layer was based on the solvent casting/particulate leaching (SCPL) modified with centrifugation. Without the step of centrifugation, the distribution of the salt particles was not uniform within the polymer solution, and the degree of interconnection between the salt particles was not well controlled. Using the centrifugal treatment, the pore distribution became uniform and the pore interconnectivity was improved even at a high polymer solution concentration (20%) as the maximal salt weight was added in the polymer solution. The titanium surfaces were modified by alkli and heat treatment, followed by functionlisation using hydrogen peroxide. A silane coupling agent was coated before the application of the dense PU pre-layer and the porous PU top layer. The ability of the porous top layer to grow and retain the endothelial cells was also assessed through cell culture techniques. The bonding strengths of the PU coatings to the modified titanium substrates were measured and related to the surface morphologies. The outcome of the project is that it has laid a foundation to achieve the strategy of endothelialisation for the blood compatibility of medical devices. This thesis is divided into seven chapters. Chapter 2 describes the current state of the art in the field of surface modification in cardiovascular devices such as ventricular assist devices (VADs). It also analyses the pros and cons of the existing coatings, particularly in the context of this research. The surface coatings for VADs have evolved from early organic/ inorganic (passive) coatings, to bioactive coatings (e.g. biomolecules), and to cell-based coatings. Based on the commercial applications and the potential of the coatings, the relevant review is focused on the following six types of coatings: (1) titanium nitride (TiN) coatings, (2) diamond-like carbon (DLC) coatings, (3) 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer coatings, (4) heparin coatings, (5) textured surfaces, and (6) endothelial cell lining. Chapter 3 reviews the polymer scaffolds and one relevant fabrication method. In tissue engineering, the function of a polymeric material is to provide a 3-dimensional architecture (scaffold) which is typically used to accommodate transplanted cells and to guide their growth and the regeneration of tissue. The success of these systems is dependent on the design of the tissue engineering scaffolds. Chapter 4 describes chemical surface treatments for titanium and titanium alloys to increase the bond strength to polymer by altering the substrate surface, for example, by increasing surface roughness or changing surface chemistry. The nature of the surface treatment prior to bonding is found to be a major factor controlling the bonding strength. By increasing surface roughness, an increase in surface area occurs, which allows the adhesive to flow in and around the irregularities on the surface to form a mechanical bond. Changing surface chemistry also results in the formation of a chemical bond. Chapter 5 shows that bond strengths between titanium and polyurethane could be significantly improved by surface treating the titanium prior to bonding. Alkaline heat treatment and H2O2 treatment were applied to change the surface roughness and the surface chemistry of titanium. Surface treatment increases the bond strength by altering the substrate surface in a number of ways, including increasing the surface roughness and changing the surface chemistry. Chapter 6 deals with the characterization of the polyurethane scaffolds, which were fabricated using an enhanced solvent casting/particulate (salt) leaching (SCPL) method developed for preparing three-dimensional porous scaffolds for cardiac tissue engineering. The enhanced method involves the combination of a conventional SCPL method and a step of centrifugation, with the centrifugation being employed to improve the pore uniformity and interconnectivity of the scaffolds. It is shown that the enhanced SCPL method and a collagen coating resulted in a spatially uniform distribution of cells throughout the collagen-coated PU scaffolds.In Chapter 7, the enhanced SCPL method is used to form porous features on the polyurethane-coated titanium substrate. The cavities anchored the endothelial cells to remain on the blood contacting surfaces. It is shown that the surface porosities created by the enhanced SCPL may be useful in forming a stable endothelial layer upon the blood contacting surface. Chapter 8 finally summarises the entire work performed on the fabrication and analysis of the polymer-Ti bonding, the enhanced SCPL method and the PU microporous surface on the metallic substrate. It then outlines the possibilities for future work and research in this area.

Selective growth of carbon nanotubes on bare silicon : MWNT sinthesys on patterned substrates without predeposition of metal catalyst

Carbon nanotubes (CNTs) are expected to become the ideal constituent of many technologes, in particular for future generation electronics. This considerable interest is due to their unique electrical and mechanical properties. They show indeed super-high current-carrying capacity, ballistic electron transport and good field-emission properties. Then, these superior features make CNTs the most promising building blocks for electronic devices, as organic solar cells and organic light emitting devices (OLED). By using Focused Ion Beam (FIB) patterning it is possible to a obtain a high control on position, relative distances and diameter of CNTs. The present work shows how to grow three-dimensional architecture made of vertical-aligned CNTs directly on silicon. Thanks to the higher activity of a pre-patterned surface the synthesis process results very quick, cheap and simple. Such large area growths of CNTs could be used in preliminary test for application as electrodes for organic solar cells.

Towards controlled growth of carbon nanotubes from germanium on nanoindented silicon substrates

In this paper, we report on a metal-catalyst-free synthesis of carbon nanotubes (CNTs) on a pre-patterned Si(001) surface. Arrays of triangular-shaped holes were created by nanoindentation in specific sites of the sample. After germanium deposition and chemical vapor deposition (CVD) of acetylene, a few CNTs nucleated and grew from germanium nanoparticles. These results illustrate that it is possible to control the growth of CNTs without the use of any metal catalyst. By leading the assembly of Ge nanoparticles with a patterning technique, a precise control over the growth order is also attainable.